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Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC.

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

Material and Device Analysis 

for Efficiency Improvement in 

Epitaxial Crystalline Solar Cells

Cooperative Research and Development 

Final Report

CRADA Number: CRD-11-433

NREL Technical Contact: Bhushan Sopori

CRADA Report

NREL/TP-5200-61158

January 2014
NOTICE

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Cover Photos: (left to right) photo by Pat Corkery, NREL 16416, photo from SunEdison, NREL 17423, photo by Pat Corkery, NREL 

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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

Cooperative Research and Development Final Report

In accordance with Requirements set forth in Article XI.A(3) of the CRADA document, this document is 

the final CRADA report, including a list of Subject Inventions, to be forwarded to the Office of Science 

and Technical Information as part of the commitment to the public to demonstrate results of federally 

funded research.

CRADA Number: CRD-11-433

CRADA Title: Material and Device Analysis for Efficiency Improvement in Epitaxial 

Crystalline Solar Cells

Parties to the Agreement: Crystal Solar

Joint Work Statement Funding Table Showing DOE Commitment:

Estimated Costs NREL Shared Resources

Year 1 $ 5,000.00

Year 2 $ 00.00

Year 3 $ 00.00

TOTALS $ 5,000.00

Abstract of CRADA Work:

Crystal Solar has a novel approach for producing low-cost, monocrystalline silicon wafers that are 

capable of yielding high-efficiency solar cells. The approach involves epitaxial growth of the substrate 

and a proprietary lift-off technology. Crystal Solar will send selected wafers and cells to NREL for 

characterization and analyses. NREL will apply a variety of techniques to help identify mechanism(s) that 

limit the cell efficiency and suggest suitable approaches for mitigation.

Summary of Research Results:

The work performed under this CRADA relates to characterization of defects and impurities in the 

Epiliftoff wafers produced by Crystal Solar. It was found that epitaxially grown thick silicon layers can 

have dislocations and stacking faults as the crystal defects. These defects significantly degrade the solar 

cell performance. To produce material for high efficiency solar cells, one must control the epi growth 

conditions to minimize crystal defects.

Subject Inventions Listing: None

Report Date: 12/6/13

Responsible Technical Contact at Alliance/NREL: Bhushan Sopori

This document contains NO confidential, protectable, or proprietary information.